Valve leaflet attachment in collapsible prosthetic valves

ABSTRACT

A prosthetic heart valve includes a stent having a collapsed condition and an expanded condition. The stent includes a plurality of cells, each cell being formed by a plurality of struts, and a plurality of commissure features. The heart valve further includes a valve assembly secured to the stent and including a cuff and a plurality of leaflets, each leaflet being attached to adjacent commissure features and to the stent struts and/or the cuff.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of the filing date of U.S.Provisional Patent Application No. 61/384,553 filed Sep. 20, 2010, thedisclosure of which is hereby incorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates to heart valve replacement and, inparticular, to collapsible prosthetic heart valves. More particularly,the present invention relates to collapsible prosthetic heart valveshaving unique valve leaflet attachments.

Prosthetic heart valves that are collapsible to a relatively smallcircumferential size can be delivered into a patient less invasivelythan valves that are not collapsible. For example, a collapsible valvemay be delivered into a patient via a tube-like delivery apparatus suchas a catheter, a trocar, a laparoscopic instrument, or the like. Thiscollapsibility can avoid the need for a more invasive procedure such asfull open-chest, open-heart surgery.

Collapsible prosthetic heart valves typically take the form of a valvestructure mounted on a stent. There are two types of stents on which thevalve structures are ordinarily mounted: a self-expanding stent and aballoon-expandable stent. To place such valves into a delivery apparatusand ultimately into a patient, the valve must first be collapsed orcrimped to reduce its circumferential size.

When a collapsed prosthetic valve has reached the desired implant sitein the patient (e.g., at or near the annulus of the patient's heartvalve that is to be replaced by the prosthetic valve), the prostheticvalve can be deployed or released from the delivery apparatus andre-expanded to full operating size. For balloon-expandable valves, thisgenerally involves releasing the entire valve, assuring its properlocation, and then expanding a balloon positioned within the valvestent. For self-expanding valves, on the other hand, the stentautomatically expands as the sheath covering the valve is withdrawn.

Despite the various improvements that have been made to collapsibleprosthetic heart valves, the currently available devices suffer fromsome shortcomings. For example, anatomical variations between patientsmay prevent adequate coaptation of the heart valve leaflets, and mayfurther result in increased stresses at different portions of the heartvalve, leading to valve failure. In addition, conventional deliverydevices do not allow for sufficient operability of the valve leafletsduring partial deployment.

There therefore is a need for further improvements in collapsibleprosthetic heart valves and their method of manufacture. Among otheradvantages, the present invention may address one or more of theseneeds.

BRIEF SUMMARY OF THE INVENTION

The present disclosure is related to prosthetic heart valves. In oneembodiment, the prosthetic heart valve includes a stent and a valveassembly. The stent has a collapsed condition and an expanded condition,the stent having a proximal end, a distal end and a plurality of cells.Each cell is formed by a plurality of struts. The valve assembly issecured to the stent and includes a cuff and a plurality of leaflets.Each leaflet has a folded portion and is coupled to the cuff at thefolded portion.

In one example, the folded portion has a width between a folded edge anda free edge, the width being between about 0.1 mm and about 2 mm. Inanother example, the folded portion of each of the plurality of leafletsis sutured to the cuff using a whip stitch. In another example, thestent includes a plurality of commissure features and each leaflet issutured to the cuff through the folded portion with a repeating suturepattern. The pattern includes a descending seam, an ascending seam, anda vertex between the descending seam and the ascending seam. The patternis disposed solely between the commissure features and the proximal endof the stent.

In another embodiment, the prosthetic heart valve includes a valveassembly and a stent having a collapsed condition and an expandedcondition. The stent includes a plurality of cells. Each cell is formedby a plurality of struts. The valve assembly is secured to the stent andincludes a cuff and a plurality of leaflets. Each leaflet includes afirst edge adjacent to the cuff and a second edge spaced apart from thecuff. Each leaflet is attached to the stent such that at least a portionof the first edge of each leaflet is disposed along at least one strutof the stent.

BRIEF DESCRIPTION OF THE DRAWINGS

Various embodiments of the present devices are disclosed herein withreference to the drawings, wherein:

FIG. 1A is a partial side view of a conventional prosthetic heart valveshowing the strain distribution in the valve assembly;

FIG. 1B is an enlarged partial view of the conventional prosthetic heartvalve of FIG. 1A showing the strain distribution in the cuff;

FIG. 2A is a highly schematic view of a portion of a collapsibleprosthetic heart valve according to one embodiment of the presentinvention having folded leaflets sutured to the cuff;

FIG. 2B is an enlarged side view of a portion of the collapsibleprosthetic heart valve of FIG. 2A showing a folded belly flap;

FIG. 3 is a partial developed view of the collapsible prosthetic heartvalve of FIG. 2A showing the suturing pattern of the leaflets to thecuff;

FIG. 4 is an enlarged side view of a portion of the collapsibleprosthetic heart valve of FIG. 2A showing the runner region betweenancons;

FIG. 5 depicts side views of a collapsible prosthetic heart valveaccording to an embodiment of the present invention having a pocketbetween the cuff and the leaflet, and a prior art device lacking such apocket;

FIG. 6 is a partial side view of a collapsible prosthetic heart valveaccording to another embodiment of the present invention, showing thevalve assembly attached to the stent;

FIG. 7 is a highly schematic developed view of a portion of acollapsible prosthetic heart valve according to yet another embodimentof the present invention having leaflets of the valve assembly attachedto the cuff in proximity to supplemental struts of the stent;

FIG. 8A is a developed view of a portion of a collapsible prostheticheart valve according to a further embodiment of the present inventionhaving the leaflets of the valve assembly attached to the stent and anedge of the leaflets disposed substantially along several stent struts;

FIG. 8B is a partial side view of the collapsible prosthetic heart valveof FIG. 8A;

FIG. 9A is a developed view of a portion of a collapsible prostheticheart valve according to still another embodiment of the presentinvention having some portions of the leaflets of the valve assemblyattached to the stent and disposed substantially along certain stentstruts;

FIG. 9B is a partial side view of the collapsible prosthetic heart valveof FIG. 9A;

FIG. 10A is a developed view of a portion of a collapsible prostheticheart valve according to yet a further embodiment of the presentinvention in which portions of the leaflets of the valve assembly areattached to the cuff at a substantially uniform distance from the stentstruts; and

FIG. 10B is a partial side view of the collapsible prosthetic heartvalve of FIG. 10A.

Various embodiments of the present invention will now be described withreference to the appended drawings. It is to be appreciated that thesedrawings depict only some embodiments of the invention and are thereforenot to be considered limiting of its scope.

DETAILED DESCRIPTION

As used herein, the term “proximal,” when used in connection with aprosthetic heart valve, refers to the end of the heart valve closest tothe heart when the heart valve is implanted in a patient, whereas theterm “distal,” when used in connection with a prosthetic heart valve,refers to the end of the heart valve farthest from the heart when theheart valve is implanted in a patient. When used in connection withdevices for delivering a prosthetic heart valve into a patient, theterms “proximal” and “distal” are to be taken as relative to the user ofthe delivery devices. “Proximal” is to be understood as relatively closeto the user, and “distal” is to be understood as relatively farther awayfrom the user.

FIG. 1A shows a typical collapsible prosthetic heart valve 100. Theprosthetic heart valve 100 is designed to replace the function of anative aortic valve of a patient. Examples of collapsible prostheticheart valves are described in International Patent ApplicationPublication No. WO/2009/042196; U.S. Pat. No. 7,018,406; and U.S. Pat.No. 7,329,278, the disclosures of all of which are hereby incorporatedherein by reference. As discussed in detail below, the prosthetic heartvalve has an expanded condition and a collapsed condition. Although theinvention is described herein as applied to a prosthetic heart valve forreplacing a native aortic valve, the invention is not so limited, andmay be applied to prosthetic valves for replacing other types of cardiacvalves.

The prosthetic heart valve 100 includes a stent or frame 102, which maybe wholly or partly formed of any biocompatible material, such asmetals, synthetic polymers, or biopolymers capable of functioning as astent. Suitable biopolymers include, but are not limited to, elastin,and mixtures or composites thereof. Suitable metals include, but are notlimited to, cobalt, titanium, nickel, chromium, stainless steel, andalloys thereof, including nitinol. Suitable synthetic polymers for useas a stent include, but are not limited to, thermoplastics, such aspolyolefins, polyesters, polyamides, polysulfones, acrylics,polyacrylonitriles, polyetheretherketone (PEEK), and polyaramides. Thestent 102 may have an annulus section 110, an aortic section (notshown), and an intermediate section disposed between the annulus andaortic sections. Each of the annulus section 110, the intermediatesection, and the aortic section of the stent 102 includes a plurality ofcells 112 connected to one another around the stent. The annulus section110, the intermediate section, and the aortic section of the stent 102may include one or more annular rows of cells 112 connected to oneanother. For instance, the annulus section 110 may have two annular rowsof cells 112. When the prosthetic heart valve 100 is in the expandedcondition, each cell 112 may be substantially diamond shaped. Regardlessof its shape, each cell 112 is formed by a plurality of struts 114. Forexample, a cell 112 may be formed by four struts 114.

The stent 102 may include commissure features or commissure posts (notshown) connecting at least two cells 112 in the longitudinal directionof the stent 102. The commissure features may include eyelets thatfacilitate the suturing of a valve assembly 104 to the stent 102.

The prosthetic heart valve 100 also includes a valve assembly 104attached inside the annulus section 110 of the stent 102. United StatesPatent Application Publication No. 2008/0228264, filed Mar. 12, 2007,and United States Patent Application Publication No. 2008/0147179, filedDec. 19, 2007, the entire disclosures of both of which are herebyincorporated herein by reference, describe suitable valve assemblies.The valve assembly 104 may be wholly or partly formed of any suitablebiological material or polymer. Examples of biological materialssuitable for the valve assembly 104 include, but are not limited to,porcine or bovine pericardial tissue. Examples of polymers suitable forthe valve assembly 104 include, but are not limited to, polyurethane andpolyester.

The valve assembly 104 may include a cuff 106 disposed on the lumenalsurface of annulus section 110, on the ablumenal surface of the annulussection, or on both surfaces, and the cuff may cover all or part ofeither or both of the lumenal and ablumenal surfaces of the annulussection. FIG. 1A shows cuff 106 disposed on the lumenal surface ofannulus section 110 so as to cover part of the annulus section whileleaving another part thereof uncovered. In addition to the materials forforming valve assembly 104 noted above, the cuff 106 and/or any of thesutures described herein may include ultra-high-molecular-weightpolyethylene. The valve assembly 104 may further include a plurality ofleaflets 108 which collectively function as a one-way valve.

The cuff 106 of the prosthetic heart valve 100 of FIG. 1A tends toexperience relatively high strain and/or stress at certain locations. Insuch heart valves 100, the weight of the leaflets 108 may subject thecuff 106 to a load in the direction indicated by arrow L, shown in FIG.1B. This load may cause an abnormally high stress and/or strain on thecuff. To manage the increased stress and strain on the cuff 106, someconventional heart valves 100 have made the cuff 106 thicker. However,thicker cuffs generally lead to a larger heart valve that is moredifficult to deliver and implant. Moreover, a bulky prosthetic heartvalve is typically incapable of being tested in vivo.

Another method of redistributing the load has been to attach theleaflets to the struts. This too has been problematic. For a host ofreasons outlined below, in accordance with some embodiments of thepresent invention, it may be advantageous to attach the leafletssubstantially entirely to the cuff and not to the struts.

First, in certain procedures, collapsible valves may be implanted in anative valve annulus without first resecting the native valve leaflets.The collapsible valves may have critical clinical issues because of thenature of the stenotic leaflets that are left in place. Additionally,patients with uneven calcification, bi-cuspid disease, and/or valveinsufficiency may not be able to be treated well, if at all, with thecurrent collapsible designs.

Implantation of a prosthetic valve adjacent unevenly calcified leafletscould lead to several problems such as: (1) perivalvular leakage (PVleak), (2) valve migration, (3) mitral valve impingement, (4) conductionsystem disruption, (5) coronary blockage, etc., all of which can haveseverely adverse clinical outcomes. To reduce these adverse events, theoptimal valve would seal and anchor adequately without the need forexcessive radial force, protrusion into the left ventricular outflowtract (LVOT), etc., that could harm nearby anatomy and physiology.Embodiments of the present invention which attach the leaflets mainly tothe cuff are able to achieve better coaptation of the leaflets, reducingthe risk of leakage.

Second, the annulus section of the prosthetic valve may have a generallyregular cylindrical shape by which is meant that the structure has agenerally circular cross-section with a substantially constant diameteralong its length. When placed in the annulus of a native heart valve,such as, for example, the tricuspid aortic valve, and expanded, asubstantially fluid-tight fit should result. However, the native valveannulus may not be circular, and, in fact, may vary from patient topatient, as may the shape of the aortic sinus or aorta, the angle of thejunction between the valve annulus and the aortic sinus, and other localanatomical features. When a prosthetic valve is deployed and expanded,it must accommodate these anatomical variations in order to functionproperly. This may result in distortion of the shape of the stent and/orvalve assembly, and the repositioning of leaflets relative to oneanother, which can affect the coaptation of these leaflets.

As the stent of a collapsible prosthetic heart valve distorts duringimplantation, during beating of the heart, or because of irregularitiesin the patient's anatomy or the condition of the native valve, suchdistortion may be translated to the valve assembly, such that not all ofthe valve leaflets meet to form effective coaptation junctions. This canresult in leakage or regurgitation and other inefficiencies which canreduce cardiac performance. Moreover, if the prosthetic valve is notplaced optimally and the valve leaflets are not coapting as intended,other long term effects, such as uneven wear of the individual leaflets,can be postulated.

Prosthetic valves in accordance with certain aspects of the presentinvention, however, can function properly notwithstanding the distortionof the stent and/or valve assembly because the leaflets aresubstantially attached to the cuff and not to the stent. Without wishingto be held to any particular theory, it is believed that a valve designhaving leaflets mostly sewn to the cuff may be better able to adjust toless than perfect annulus geometry. Such leaflet-cuff arrangements maybe more insulated from imperfect geometry-induced stresses on the strutsthan those arrangements having the leaflets completely or predominantlysewn to the stent. Thus, the possibility of uneven wear due toanatomical variations is greatly reduced by attaching the leafletsentirely or predominantly to the cuff.

Moreover, by sewing the leaflet to the cuff and not to the struts,greater flexibility is afforded in positioning the leaflets and invarying the height, width and shape of the leaflets. Specifically,because the leaflets in conventional heart valves are attached to thestruts, the leaflet shape and positioning is limited by the location ofthe struts. In contrast, suturing patterns may be varied with greaterbenefits when the leaflets are attached predominantly to the cuff.

Having outlined some of the benefits of a leaflet-cuff attachment, thefeatures of this embodiment will be described in connection with theprosthetic heart valve 300 shown in FIGS. 2A-5. It will also be notedthat while the inventions herein described are predominately discussedin terms of a tricuspid valve and a stent having a shape as illustratedin FIGS. 2A-5, the valve could be a bicuspid valve, such as the mitralvalve, and the stent could have different shapes, such as a flared orconical annulus section, a less-bulbous aortic section, and the like,and a differently shaped intermediate section.

In attaching the plurality of leaflets, each leaflet 308 may be firstattached to the stent 302 by suturing through the eyelets of commissurefeatures 316. Additional examples of leaflet-commissure featureattachments are disclosed in U.S. patent application Ser. No.13/216,124, entitled “Leaflet Suturing to Commissure features forProsthetic Heart Valve”, filed on Aug. 23, 2011, the disclosure of whichis hereby incorporated by reference as if fully set forth herein. Inaddition to the commissure features 316, the plurality of leaflets maybe attached to the cuff 306 as described below.

FIGS. 2A, 2B and 3 illustrate one such embodiment in which the leaflets308 have been attached by suturing substantially entirely to the cuff306. In the illustrated embodiment, the leaflets 308 are coupled to thecuff 306 after they have been attached to the commissure features 316.It will be understood, however, that the order of attachment may bechanged or varied as necessary by those skilled in the art.

FIGS. 2A and 2B illustrate a cuff 306 and one or more leaflets 308. Eachleaflet 308 includes a proximal end 352 for attachment to the cuff 306and a free distal end 354 for coapting with the other leaflets to form aclosed valve. As seen in FIG. 2A, each leaflet 308 may be folded uponitself at the proximal end 352 to form a belly flap 356 for attachingthe leaflet to the cuff 306. The belly flap 356 may be formed by foldingthe proximal edge of the leaflet 308 once over itself toward the cuff306 so that the belly flap is disposed between a portion of the leafletand the cuff. The width x of the belly flap 356 between folded edge 356a and free edge 356 b may vary from valve to valve, and also within avalve. For example, the belly flap 356 may have a width x between about0.1 mm and about 2.0 mm. Variants of the belly flap 356 are alsocontemplated herein. For example, the belly flap 356 may be formed byfolding the leaflet 308 more than once (e.g., twice, thrice or more).Additionally, the belly flap 356 may be formed along only a portion ofthe proximal edge of the leaflet 308 if the entire proximal edge willnot be sutured to the cuff 306. Still further, the belly flap 356 may beformed by folding the proximal edge of the leaflet 308 away from thecuff 306, rather than toward the cuff as described above.

After folding each leaflet 308 to form a belly flap 356, the leaflets308 may be attached to the cuff 306 in accordance with the attachmentpattern shown in FIG. 3. For the purpose of clarity, the leaflet-cuffattachment pattern will be described with reference to FIG. 3 withoutshowing a belly flap. It will be understood, however, that a belly flapas described above and shown in FIGS. 2A and 2B may be disposed eitheron the inner or lumenal side of the leaflet 308 or between the leafletand the cuff 306.

The prosthetic heart valve 300 of FIG. 3 includes a stent or frame 302having an annulus section 310 and an aortic section (not shown). Each ofthe annulus section 310 and the aortic section of the stent 302 includesa plurality of cells 312 connected to one another around thecircumference of the stent. The annulus section 310 and the aorticsection of the stent 302 may include one or more annular rows of cells312 connected to one another. For instance, the annulus section 310 mayhave two annular rows of cells 312. When the prosthetic heart valve 300is in the expanded condition, each cell 312 may be substantially diamondshaped. Regardless of its shape, each cell 312 is formed by a pluralityof struts 314. For example, a cell 312 may be formed by four struts 314.

The stent 302 may include commissure features 316 connecting at leasttwo cells 312 in the longitudinal direction of the stent. The commissurefeatures 316 may include eyelets for facilitating the suturing of avalve assembly 304 to the stent 302.

A cuff 306 maybe disposed on the lumenal surface of annulus section 310,on the ablumenal surface of the annulus section, or on both surfaces,and the cuff may cover all or part of either or both of the lumenal andablumenal surfaces of the annulus section. FIG. 3 shows cuff 306disposed on the lumenal surface of annulus section 310 so as to coverpart of the annulus section while leaving another part thereofuncovered. In particular, the cuff 306 covers substantially all of theannulus section 310 between the proximal edge of stent 302 and thecommissure features 316, but a much lesser area of the annulus sectionbetween the commissure features. The valve assembly 304 may furtherinclude a plurality of leaflets 308 which collectively function as aone-way valve.

As shown in FIG. 3, struts 314 a, 314 b, and 314 c may be connected toone another in substantially end-to-end fashion diagonally along threecells 312, beginning with an end of the strut 314 a connected to acommissure feature 316 a and ending with an end of strut 314 c connectedto an end of strut 314 d. Struts 314 c and 314 d are part of the samecell 312 a. Struts 314 d, 314 e, and 314 f may be connected to oneanother in substantially end-to-end fashion diagonally along three cells312, beginning with an end of the strut 314 f connected to a commissurefeature 316 b and ending with the connection between an end of strut 314d and an end of strut 314 c. For the sake of completeness, cell 312 aincludes strut 314 c connected to strut 314 d at the bottom of the celland struts 314 g and 314 h connected to one another at the top of thecell, as well as to struts 314 d and 314 c, respectively.

In addition to being connected to one another around the circumferenceof stent 302, cells 312 may be connected to one another in thelongitudinal direction of the stent. Two adjacent struts, for examplestruts 314 e and 314 g, merge near the bottom of the cell beforesplitting off into two different struts. The meeting point where twostruts 314 merge or where one strut 314 splits into two components isdefined as an ancon 320. The ancons 320 in two longitudinally adjacentrows of cells 312 may be joined by runners r.

The plurality of leaflets 308 may be attached directly to the cuff 306near struts 314 a, 314 b, 314 e, and 314 f, such as by suturing. Asshown in FIG. 3, the leaflets 308 may be attached to cuff 306 justproximal of the aforementioned struts 314 along an attachment line S.Specifically, a distance y may be maintained between the attachment lineS and the struts 314. This distance may be less than or equal to 2.0 mm,and may vary as necessary. By attaching the leaflets 308 to the cuff 306in a pattern that follows the curvature of some of the struts 314,stress on the cuff 306 may be reduced while maintaining a degree offlexibility.

As described above, the attachment line S includes an initial descentfrom just proximal of commissure feature 316 a and continues proximal ofstruts 314 a and 314 b while substantially maintaining a distance y fromthe struts. At the proximal end of strut 314 b, the attachment line Sbegins to flatten out, passing through cell 312 a, and then ascendsproximal of struts 314 e and 314 f, maintaining substantially the sameor a similar distance y from the struts, until it reaches a point justproximal of commissure feature 316 b. Between the descending seam andthe ascending seam, the attachment line crosses a pair of runners r1 andr2 and forms a vertex therebetween.

FIG. 4 shows runners r1 and r2 in more detail. As described above, theattachment line S generally descends from a point just proximal ofcommissure feature 316 a, travels proximal of struts 314 a and 314 b,crosses runner r1, changes direction and crosses runner r2, and thenascends proximal of struts 314 e and 314 f until it reaches a point justproximal of commissure feature 316 b.

The foregoing discussion describes the general pattern by which leaflets308 may be attached directly to cuff 306. Having generally described theattachment pattern, the following description provides one exemplarymethod of suturing the leaflets 308 to the cuff 306. As will beunderstood by those of ordinary skill in the art, the description belowis for one of many possible methods, and the distances, configurationsand arrangements described are merely exemplary and not limiting. Forexample, instead of using a single suture around the perimeter of thevalve assembly, leaflets 308 may be sutured to the cuff 306 using aplurality of sutures.

Initially, the leaflets 308 are aligned with the cuff 306 and struts 314at the desired locations, typically in the annulus section 310. The endsof the distal free edge of each leaflet 308 are then sutured to both thecuff 306 and the stent 302 through the eyelets of an adjacent pair ofcommissure features 316. The belly of the leaflets 308 may then besutured to the cuff 306 around the circumference of the heart valve 300proximal of the commissure features 316.

With reference to FIG. 3, a first leaflet 308 may be sutured to the cuff306 by first passing a suture from the ablumenal side of the cuff 306 tothe lumenal side of the cuff approximately 0.5 mm to 2.0 mm proximal ofa first commissure feature 316 a. This location will be referred to asthe origination stitch. A suture tail segment maybe maintained at theorigination stitch in order to tie to the end of the pattern afterstitching around the circumference of the cuff 306 has been completed.The leaflet 308 may then be stitched to the cuff 306 using a series ofwhip stitches. Stitches from the ablumenal side to the lumenal side ofthe heart valve 300 pass through the cuff 306 only. Stitches from thelumenal side to the ablumenal side of the heart valve 300 pass throughboth layers of the leaflet 308 (e.g., the leaflet as well as the foldedbelly flap 356) and the cuff 306. Thus, with each whip stitch the sutureis passed from the ablumenal side to the lumenal side of the heart valve300 through the cuff 306 only and then through both layers of theleaflet 308 and the cuff 306 from the lumenal side of the valve to theablumenal side thereof.

The stitch spacing and bite size may vary from about 0.5 mm to about 2.0mm, and preferably is about 1.0 mm. Stitches may be approximatelyperpendicular to the leaflet edge when viewed from the side of the valve300. Beginning just proximal of commissure feature 316 a, the suturesmay travel approximately at a distance y proximal of struts 314 a and314 b, across a first runner r1, form a vertex, across a second runnerr2, and approximately at a distance y proximal of struts 314 e and 314 funtil reaching a point just proximal of commissure feature 316 b. Thesutures may begin at a point A about 0.5 mm to about 2.0 mm proximal ofcommissure feature 316 a, and may end at a point B, about 0.5 mm toabout 2.0 mm proximal of commissure feature 316 b.

Thus, between the first commissure feature 316 a and the secondcommissure feature 316 b, a substantially symmetrical parabola is formedby the suture line S. This parabolic pattern may be repeated betweencommissure features 316 b and 316 c and between commissure features 316c and 316 a around the circumference of the cuff 306, ending at or nearpoint A where the suture line S began. Upon returning to point A, theconcluding tail of the suture line S may be tied to the originationstitch using a single double knot.

FIG. 5 shows a comparison between a heart valve 300 according to oneembodiment of the present invention and a conventional heart valve 300′.As can be seen the heart valve 300 according to the present inventionincludes an enlarged cuff 306 that overlaps with a portion of theleaflets 308. In contrast, the heart valve 300′ includes no such overlapbetween the leaflets 308′ and the cuff 306′. Rather, the leaflets 308′and cuff 306′ are attached to one another in an edge-to-edge fashion.The leaflet-cuff overlap provided by the heart valve 300 of the presentinvention forms a pocket P and allows for the suture pattern discussedabove. Pocket P formed by the leaflet-cuff overlap minimizesperivalvular leakage and acts as a tissue buffer for improveddurability. Compared to conventional devices, this configuration alsoprovides a larger buffer against fretting corrosion. Thus, by providingan enlarged cuff, the stress on the cuff may be decreased, thedurability of the cuff increased and the flexibility of the heart valveincreased to allow for applications such as partial deployment of theheart valve, for example, for testing.

In this manner, by attaching the leaflets 308 to the cuff 306, a host ofbenefits as enumerated above, as well as others, may be achieved.Moreover, the description above provides one method by which stress onthe cuff can be reduced. Namely, by suturing the leaflets to the cuff,maintaining the spacing between the suture line and the struts describedabove, and passing the sutures across the runners, the load on the cuffcan be partially redistributed to the struts to prevent possible wearand/or failure. Thus, the foregoing embodiment describes one method forreducing stress on the cuff at critical junctions. This method providesa solution by suturing the leaflets to the cuff without providing athicker cuff or using different materials for the cuff.

The above embodiment notwithstanding, it will be understood that theleaflets need not be coupled only (except for the commissure features)to the cuff. In other embodiments, instead of suturing the leaflets toonly the cuff, selected regions of each leaflet, or the active proximaledge thereof, may be attached to the struts to relieve at least some ofthe stress on the cuff.

FIG. 6 shows a collapsible prosthetic heart valve 600 according toanother embodiment of the present invention. The prosthetic heart valve600 is designed to replace the function of a native aortic valve of apatient. As discussed in detail below, the prosthetic heart valve has anexpanded condition and a collapsed condition.

The prosthetic heart valve 600 includes a stent or frame 602, which maybe wholly or partly formed of any of the materials noted above forforming stent 102. The stent 602 may have an annulus section 610 and anaortic section (not shown). Each of the annulus section 610 and theaortic section of the stent 602 includes a plurality of cells 612connected to one another around the stent. The annulus section 610 andthe aortic section of the stent 602 may include one or more annular rowsof cells 612 connected to one another. For instance, the annulus section610 may have two annular rows of cells 612. When the prosthetic heartvalve 600 is in the expanded condition, each cell 612 may besubstantially diamond shaped. Regardless of its shape, each cell 612 isformed by a plurality of struts 614. For example, a cell 612 may beformed by four struts 614.

The stent 602 may include commissure features 616 connecting at leasttwo cells 612 in the longitudinal direction of the stent 602. Thecommissure features 616 may include eyelets to facilitate the suturingof a valve assembly 604 to the stent 602.

The prosthetic heart valve 600 also includes a valve assembly 604attached inside the annulus section 610 of the stent 602. The valveassembly 604 may be formed from the same materials used to form valveassembly 104 described above. The valve assembly may include a cuff 606disposed on the lumenal surface of annulus section 610, on the ablumenalsurface of the annulus section, or on both surfaces. The cuff 606 maycover all or part of either or both of the lumenal and ablumenalsurfaces of the annulus section. FIG. 6 shows cuff 606 disposed on thelumenal surface of the annulus section 610 so as to cover part of theannulus section while leaving another part thereof uncovered. Inaddition to the materials noted above for forming valve assembly 604,the cuff 606 may include ultra-high-molecular-weight polyethylene, asmay any of the sutures described herein.

The valve assembly 604 may further include a plurality of leaflets 608which collectively function as a one-way valve. A first edge 622 of eachleaflet 608 may be attached to the stent 602 by any suitable attachmentmeans, such as suturing, stapling, adhesives or the like. For example,the first edge 622 of each leaflet 608 may be sutured to the stent 602by passing strings or sutures through the cuff 606 of the valve assembly604. Optionally, portions of the first edge 622 of one or more leaflets608 may be attached solely to the cuff 606. A second edge 624 of eachleaflet 608 is free to coapt with the corresponding free edges of theother leaflets and thereby enables the leaflets to function collectivelyas a one-way valve.

Irrespective of the attachment means employed, the leaflets 608 may beattached to the stent 602 along at least some struts 614 of the stent toenhance the structural integrity of the valve assembly 604. As aconsequence of this attachment, the struts 614 help support the leaflets608 of the valve assembly 604 and may therefore reduce the strain in theleaflet-cuff junction.

As shown in FIG. 6, at least one leaflet 608 may be attached to thestent 602 so that its first edge 622 is disposed substantially alongspecific struts 614 a, 614 b, 614 c, 614 d, 614 e and 614 f located inthe annulus section 610 of the stent. That is, the edge 622 ispositioned in substantial alignment with struts 614 a, 614 b, 614 c, 614d, 614 e and 614 f. Struts 614 a, 614 b, and 614 c may be connected toone another in substantially end-to-end fashion diagonally along threecells 612, beginning with an end of the strut 614 a connected to acommissure feature 616 and ending with an end of strut 614 c connectedto an end of strut 614 d. Struts 614 c and 614 d are part of the samecell 612 and may collectively define approximately a right angle betweenthem. Struts 614 d, 614 e, and 614 f may be connected to one another insubstantially end-to-end fashion diagonally along three cells 612,beginning with an end of the strut 614 f connected to a commissurefeature 616 and ending with the connection between an end of strut 614 dand an end of strut 614 c.

As discussed above, the leaflets 608 may be attached directly to andsupported by the struts 614 a, 614 b, 614 c, 614 d, 614 e and 614 f,such as by suturing. In such event, the cuff 606 may perform little orno supportive function for the leaflets 608, and a cuff of minimumthickness may therefore be used. Minimizing the thickness of the cuff606 results in a lower volume of the valve assembly 604 in the collapsedcondition. This lower volume is desirable as it enables the prostheticheart valve 600 to be implanted in a patient using a delivery devicethat is smaller than conventional delivery devices.

With continued reference to FIG. 6, the first or proximal end 618 of thecuff 606 may substantially follow the contour of the first or proximalend 619 of the stent 602, whereas the second or distal end 620 of thecuff 606 may be disposed substantially along at least some struts 614.More particularly, the second end 620 of the cuff 606 may be disposedsubstantially along struts 614 a, 614 b, 614 e, 614 f, 614 g and 614 h,as shown in FIG. 6, so as to form a zig-zag pattern of first or upperpeaks and second or lower peaks. Strut 614 g may be connected at one endto strut 614 h, and at the other end to the intersection of struts 614 band 614 c. Strut 614 h may be connected at one end to strut 614 g, andat the other end to the intersection of struts 614 d and 614 e. Struts614 c, 614 d, 614 g and 614 h collectively form a single cell 612.Having the ends of the cuff 606 disposed substantially along thegenerally sinusoidal or zig-zag pattern of the stent struts 614 enablesthe stent struts to perform most of the supportive function for theleaflets 608, such that the cuff 606 performs little or no supportivefunction for the leaflets. Hence, the cuff 606 is not subjected to highstresses and is therefore less likely to fail during operation. Inaddition, since the material forming the stent struts 614 is strongerthan the material forming the cuff 606, the stent struts 614 may performthe supportive function for the leaflets 608 better than the cuff 606.

As a result of the foregoing configuration, all of the cells 612 in thebottom annular row 613 of cells 612 may be entirely covered by the cuff606. The cuff 606 may also entirely cover those cells 612 in a secondannular row 615 that are located directly below the commissure feature616. All of the other cells 612 in the stent 602 may be open or notcovered by the cuff 606. Hence, there may be no cells 612 which are onlypartially covered by the cuff 606.

Referring to FIG. 7, a prosthetic heart valve 700 according to anotherembodiment of the present invention includes a stent or frame 702, whichmay be similar to stent 602. The stent 702 may include one or moreannular rows of cells 712. Each cell 712 may be formed by a plurality ofstruts 714. For example, four struts 714 may form a single cell 712,which may be substantially diamond shaped when the stent 702 is in theexpanded condition.

In addition to struts 714, the stent 702 may include one or moresecondary or supplemental struts 726 extending across one or more cells712. For example, one supplemental strut 726 may extend across two cells712 located in the same annular row of cells. That is, supplementalstrut 726 may extend from the point at which cell 712 a joins cell 712b, across cells 712 b and 712 c, to the point at which cell 712 c joinscell 712 d. The supplemental struts 726 may have a serratedconfiguration, as shown in FIG. 7. Alternatively, the supplementalstruts 726 may have a curved shape.

The prosthetic heart valve 700 further includes a valve assembly 704attached inside the stent 702. The valve assembly 704 may be similar tovalve assembly 604 and may include a cuff (not shown) and a plurality ofleaflets 708 which collectively function as a one-way valve. A firstedge 722 of each leaflet 708 may be attached to the stent 702 by anysuitable attachment means, such as suturing, stapling, adhesives or thelike. The leaflet 708 may be attached to the stent 702 through the cuff.Optionally, selected portions of the first edge 722 of one or moreleaflets 708 may be attached solely to the cuff.

At least one leaflet 708 may be attached to the stent 702 so that theupper portions 728 and 730 of its edge 722 are disposed substantiallyalong struts 714 a and 714 b, respectively. Such arrangement enables thestent struts 714 to perform most of the supportive function for theleaflet 708. As a result, the cuff performs little or no supportivefunction for the leaflet 708. Hence, the cuff is not subjected to highstresses and is therefore less likely to fail during operation. Inaddition, since the material forming the stent struts 714 is strongerthan the material forming the cuff, the stent struts 714 may perform thesupportive function for the leaflet 708 better than the cuff.

The serrated or curved configuration of supplemental struts 726 may besuch as to approximate the curved shape of the lower portion 732 of theedge 722 of the leaflets 708. For example, if the supplemental strut 726has a serrated configuration, the lower portion 732 of the edge 722 ofeach leaflet 708 may extend beyond some portions of the supplementalstrut 726, while not quite reaching other portions of the supplementalstrut. The greater the number of serrations supplemental strut 726 isformed with, the more closely the supplemental strut can approximate theshape of the lower portion 732 of the edge 722. In its lower portion732, the edge 722 of each leaflet 708 may be attached to the cuff. Theproximity of the lower portion 732 of the edge 722 to the supplementalstruts 726 enables the supplemental struts to perform most of thesupportive function for the lower portion of the edge 722 of theleaflets 708. A second edge 724 of each leaflet 708 is free to coaptwith the corresponding free edges of the other leaflets and therebyenables the leaflets to function collectively as a one-way valve.

With reference to FIGS. 8A and 8B, a prosthetic heart valve 800according to yet another embodiment of the present invention includes astent or frame 802, which may be similar to stent 602. The stent 802 mayinclude an aortic section 840 and an annulus section 810. Each of theaortic section 840 and the annulus section 810 may include a pluralityof cells 812 connected to one another in one or more annular rows. Thecells 812 of the aortic section 840 may be larger than the cells of theannulus section 810. Each cell 812 is formed by a plurality of struts814. For example, each cell 812 may be formed by four struts 814 and maybe substantially diamond-shaped when the stent 802 is in an expandedcondition. The stent 802 may further include one or more commissurefeatures 816 for facilitating suturing of a valve assembly 804 to thestent. Each commissure feature 816 may interconnect two cells 812 in thesame annular row and two cells in different annular rows.

The valve assembly 804 may be attached inside the stent 802. The valveassembly 804 may include a cuff 806 and a plurality of leaflets 808which collectively function as a one-way valve. Each leaflet 808includes an edge 822, portions of which are attached to the cuff 806 andother portions of which are attached to the stent 802, and a second freeedge 824. An upper portion 828 of the edge 822 may be attached to thestent 802 so as to be disposed substantially along the path of certainstruts 814 that lead to the commissure features 816. For example, anupper portion 828 of the edge 822 of at least one leaflet 808 may beattached to, and disposed substantially along, struts 814 a and 814 b.An upper portion 828 of the edge 822 of an adjacent leaflet 808 may beattached to, and disposed substantially along, struts 814 c and 814 d.As such, struts 814 a, 814 b, 814 c and 814 d help support theseleaflets 808, thereby reducing the stress in the cuff 806. The upperportions 828 of the edges 822 of the leaflets 808 may be attached to thecommissure feature 816 and struts 814 a, 814 b, 814 c and 814 d usingsutures 850. Struts 814 b and 814 c may each have one end attached to acommissure feature 816 and each may be part of the same cell 812.Alternatively, struts 814 b and 814 c may be attached directly to oneanother. Struts 814 a and 814 b may be connected in an end-to-endfashion, and may be part of different cells 812 that are adjacent to oneanother. Similarly, struts 814 c and 814 d may be connected in anend-to-end fashion, and may be part of different cells 812 that areadjacent to one another. The lower portion 832 of the edge 822 of eachleaflet 808 may be connected to the cuff 806.

With reference to FIGS. 9A and 9B, a collapsible prosthetic heart valve900 according to an embodiment of the present invention includes a stent902, which may be similar to stent 602. The stent 902 has collapsed andexpanded conditions and includes a plurality of cells 912 connected toone another in annular rows around the stent. Each cell 912 is formed bya plurality of struts 914 and may be substantially diamond shaped whenthe stent 902 is in the expanded condition. For example, one cell 912may be formed by four interconnected struts 914.

The stent 902 may further include one or more commissure features 916that interconnect two adjacent cells 912 located in one annular row andtwo other cells 912 located in the next adjacent rows above and belowthe one row. The commissure features 916 may facilitate the suturing ofa valve assembly 904 to the stent 902.

The valve assembly 904 may include a cuff 906 attached to the stent 902.As with all embodiments described herein, the cuff 906 may be disposedon the lumenal surface of the stent, the ablumenal surface of the stent,or on both surfaces. In addition to the cuff 906, the valve assembly 904includes a plurality of leaflets 908 attached to the stent 902 and thecuff 906, and collectively defining a one-way valve. Each leaflet 908includes a first edge 922 attached to both the cuff 906 and the stent902 and a second free edge 924. At least one leaflet 908 may be attachedto the cuff 906 and the stent 902 so that the upper portions 928 of itsedge 922 are substantially disposed along the path of certain struts914. As shown in FIGS. 9A and 9B, one upper portion 928 of the edge 922of one leaflet 908 may be connected to a commissure feature 916 and mayinclude an intermediate portion disposed along and connected to a strut914 b spaced from the commissure feature. Between strut 914 b andcommissure feature 916, the upper portion 928 of the edge 922 may beconnected to the cuff 906 within the area of cell 912 a. Moreparticularly, an end section A of the upper portion 928 of the edge 922may follow a substantially direct path between the commissure feature916 and an end of stent strut 914 b. Similarly, one upper portion 928 ofthe edge 922 of an adjacent leaflet 908 may be connected to thecommissure feature 916 and may be disposed along and connected to astrut 914 d spaced from the commissure feature. Between strut 914 d andcommissure feature 916, the upper portion 928 of the edge 922 of thisleaflet may be connected to the cuff 906 within the area of cell 912 a.That is, an end section A of the upper portion 928 of the edge 922 ofthis second leaflet may follow a substantially direct path between thecommissure feature 916 and an end of stent strut 914 d. The edges 922 ofthe leaflets may be connected to the commissure features 916 and to thestruts 914 b and 914 d using sutures 950. The end sections A of theedges 922 of the leaflets 908 may be connected to the cuff 906 usingsutures, bonding or other known techniques. The lower or middle portion932 of the edge 922 of each leaflet 908 may be connected to the cuff 906in a location not aligned with any strut.

With reference to FIGS. 10A and 10B, a prosthetic heart valve 1000according to an embodiment of the present invention includes a stent orframe 1002 having an expanded condition and a collapsed condition. Thestent 1002 may be similar to the stent 602 and includes a plurality ofcells 1012 arranged in one or more annular rows. Each cell 1012 isformed by a plurality of struts 1014 and may be substantiallydiamond-shaped when the stent 1002 is in the expanded condition. Forexample, each cell 1012 may be formed by four interconnected struts1014.

A valve assembly 1004 is attached inside the stent 1002 and may includea cuff 1006 and a plurality of leaflets 1008, which function as aone-way valve. The leaflets 1008 may be attached to the cuff 1006 andthe stent 1002. Specifically, each leaflet 1008 may include an edge 1022attached to the cuff 1006 and the stent 1002 and a free edge 1024. Theupper portion 1028 of the edge 1022 may be attached to a commissurefeature 1016 and to the cuff 1006 along a path substantially parallelto, but spaced from, some struts 1014. More particularly, one section ofthe upper portion 1028 of the edge 1022 of one leaflet 1008 may bedisposed substantially along a direct path between commissure feature1016 and a runner 1015 a between two adjacent cells 1012 in annularbottom row 1017 of cells. One section of the upper portion 1028 of theedge 1022 of an adjacent leaflet 1008 may be disposed substantiallyalong a direct path between commissure feature 1016 and a runner 1015 bbetween two adjacent cells 1012 in the bottom row 1017 of cells. Theupper portions 1028 of the edges 1022 may be spaced from some struts1014 by a substantially uniform distance, i.e., the upper portions ofthe edges may be substantially parallel to these struts. For example, atleast part of the upper portion 1028 of the edge 1022 of one leaflet1008 may be spaced a substantially uniform distance from struts 1014 aand 1014 b, while the upper portion 1028 of the edge 1022 of theadjacent leaflet may be spaced a substantially uniform distance fromstruts 1014 c and 1014 d. This distance may be about 2 mm in preferredembodiments. The lower portions 1032 of the first edge 1022 of eachleaflet 1008 may intersect the runners 1015 along the bottom row 1017 ofcells 1012.

In operation, any of the embodiments of the prosthetic heart valvedescribed above may be used to replace a native heart valve, such as theaortic valve. The prosthetic heart valve may be delivered to the desiredsite (e.g., near a native aortic annulus) using any suitable deliverydevice. During delivery, the prosthetic heart valve is disposed insidethe delivery device in the collapsed condition. The delivery device maybe introduced into a patient using a transfemoral, transapical ortransseptal approach. Once the delivery device has reached the targetsite, the user may deploy any of the prosthetic heart valves describedabove. Upon deployment, the prosthetic heart valve expands into secureengagement within the native aortic annulus. When the prosthetic heartvalve has been properly positioned inside the heart, it works as aone-way valve, allowing blood to flow in one direction and preventingblood from flowing in the opposite direction.

Although the invention herein has been described with reference toparticular embodiments, it is to be understood that these embodimentsare merely illustrative of the principles and applications of thepresent invention. It is therefore to be understood that numerousmodifications may be made to the illustrative embodiments and that otherarrangements may be devised without departing from the spirit and scopeof the present invention as defined by the appended claims.

It will be appreciated that the various dependent claims and thefeatures set forth therein can be combined in different ways thanpresented in the initial claims. It will also be appreciated that thefeatures described in connection with individual embodiments may beshared with others of the described embodiments.

The invention claimed is:
 1. A prosthetic heart valve, comprising: astent having a collapsed condition and an expanded condition, the stentextending in a longitudinal direction between a proximal end and adistal end and including a plurality of cells arranged in annular rowsaround a circumference of the stent, each cell being formed by aplurality of struts so that the cells have substantially a diamond shapewith a first end pointing toward the distal end of the stent and asecond end pointing toward the proximal end of the stent, the pluralityof cells including subsets of cells in which the first end of one cellis aligned in the longitudinal direction with the second end of anothercell, the plurality of struts including ancons at which multiple strutsmerge; a plurality of commissure features disposed on the stent, each ofthe commissure features being disposed in the longitudinal directionbetween the first end of the one cell and the second end of the anothercell so that the commissure feature is aligned in the longitudinaldirection with the first end of the one cell and the second end of theanother cell; and a valve assembly secured to the stent and including acuff and a plurality of leaflets disposed between the plurality ofcommissure features and the proximal end of the stent, each of theplurality of leaflets being sutured only to the cuff between respectivepairs of the commissure features with a repeating pattern of sutures,the pattern of sutures including a descending seam at a spaced distancefrom one group of the plurality of struts, an ascending seam at thespaced distance from another group of the plurality of struts, and avertex between the descending seam and the ascending seam, the patternof sutures passing between two pairs of adjacent ancons near the vertex.2. The prosthetic heart valve according to claim 1, wherein each sutureis spaced from an adjacent suture by between about 0.5 mm and about 2.0mm.
 3. The prosthetic heart valve according to claim 1, wherein an endof the descending seam is spaced between about 0.5 mm and about 2.0 mmproximal of a first commissure feature, and an end of the ascending seamis spaced between about 0.5 mm and about 2.0 mm proximal of a secondcommissure feature.
 4. The prosthetic heart valve according to claim 1,wherein the spaced distance is less than about 2.0 mm.
 5. The prostheticheart valve according to claim 1, wherein the pattern of sutures is arepeating parabolic pattern.
 6. The prosthetic heart valve according toclaim 1, wherein each of the plurality of leaflets overlaps with aportion of the cuff to form a pocket between the cuff and each of theplurality of leaflets.
 7. A prosthetic heart valve, comprising: a stenthaving a collapsed condition and an expanded condition, the stentincluding a plurality of cells, each cell being formed by a plurality ofstruts; and a valve assembly secured to the stent and including a cuffand a plurality of leaflets, each leaflet including a first edgeadjacent to the cuff and a second edge spaced apart from the cuff, thefirst edge of each leaflet having end portions, a middle portion, andintermediate portions between the middle portion and the end portions,the end portions and the middle portion of the first edge of eachleaflet being connected only to the cuff, and the intermediate portionsof the first edge of each leaflet being connected to selected ones ofthe plurality of struts.
 8. A prosthetic heart valve, comprising: astent having a collapsed condition and an expanded condition, the stentincluding a plurality of cells, each cell being formed by a plurality ofstruts; a plurality of commissure features disposed on the stent; and avalve assembly secured to the stent and including a cuff and a pluralityof leaflets, the cuff having a proximal end and a distal end, the distalend defining a plurality of first peaks and a plurality of second peaks,the first peaks and the second peaks intersecting at intersectionpoints, each of the first peaks extending between a pair of theintersection points and a respective one of the commissure features, andthe second peaks extending between adjacent ones of the first peaks. 9.The prosthetic heart valve according to claim 8, wherein each of thefirst peaks extends from the pair of intersection points by a firstdistance to the respective commissure feature, and each of the secondpeaks extends from a pair of the intersection points by a distance lessthan the first distance.